The goal of the proposed research is to explore the relationship between epinephrine (E) and norepinephrine (NE) levels in blood plasma and the reactions of Type a and Type B individuals to uncontrollable stressors. Guided by previous theory and research, it is expected that compared to Type Bs, the reactions of coronary-prone Type As to brief uncontrollable stress (i.e., hyper-responsiveness) will be accompanied by specific elevations in plasma NE. Greater depletion of NE and greater increments in E are expected to accompany the hypo-responsiveness of Type As to prolonged exposure to stress. These general hypotheses will be tested in a series of laboratory experiments with "healthy" college-age males and working adults. While this research is designed as a first step toward elucidating possible mechanisms underlying a linkage Pattern A and stress, it also has implications for questions relating to the etiology of coronary disease. Previous research suggests that catecholamines may potentiate atherogenesis and, to this extent, the proposed studies will shed light on processes whereby Pattern A and stress lead to cardiovascular pathology. Other theoretical and practical implications of the research are discussed in the body of the proposal, including general issues relating to impact of behavioral variables on coronary disease.